Why would loading a XAML file fail on a brand project?

This is the first time I have started a silverlight project on the current machine I am on with Visual Studio 2010. Until now, I have been programing ni ASP.NET.

When I first tried to start a new Silverlight project, I was told I needed to install a fresh copy of Silverlight. I had to uninstall Silverlight as well as my versions of the Silverlight SDK. After uninstalling and reinstalling (now I have Microsoft Silverlight 5.1.20513.0 and Silverlight 4 SDK 4.0.50826.0) I was finally able to create a Silverlight Project. But the XAML code instantly failed to load in the IDE